Add note about how configurate the file into config.js.sample

config/config.js.sample

@@ -2,6 +2,10 @@
  *
  * By Michael Teeuw http://michaelteeuw.nl
  * MIT Licensed.
+ *
+ * For more information how you can configurate this file
+ * See https://github.com/MichMich/MagicMirror#configuration
+ *
  */
 
 var config = {